Bought this lens before the most recent price hikes. I paid $2070 shipped from Amazon. The build quality is outstanding. It feels like a piece of high precision industrial equipment to handle... which is basically what it is. The locking lens hood is also a nice improvement. This lens takes the 1.4x TC II and III very well. It also does well with the 2.0x TC but the performance hit is much more noticeable. The weight can be a little much when combined with a 1 series body. Even though it's a relatively small lens I would recommend either a monopod or a sling style strap if you plan on carrying this lens for hours at a time. Highly recommended, it's the best short/mid range tele zoom there is.

Pretty much everything. Sharp, good DoF, fast focus, reliable. Built like a tank.

Cons:

A little vulnerable to chromatic aberration on very bright days.

I avoided buying this lens for many years because I've always heard that the quality was hit and miss. I finally decided to get one because I really needed a walkaround zoom lens for car shows and for very short range panning shots at motorsports events. All I can say is that I wish I had bought this lens years ago. The focus speed is very fast. It's built like a tank. It's razor sharp. I could not be happier. Mine is a UX date code, so perhaps Canon fixed whatever inconsistencies there were in manufacturing.